| 摘要 |
PURPOSE:To improve the durability and safety by preventing the wear of the pump seal due to the air intrusion by controlling the delivery rate of the pump by switching the pump operation from high to low based on the signal from a water level sensor and a water flow rate control valve. CONSTITUTION:As the water level in the tank 12 drops, a control means 26 causes a water flow rate control valve 25 to be fully opened upon going OFF of a low level switch 23a so as to increase the flow rate. At this time, if the delivery rate of a pump 14 is greater, the switch 23a stays OFF. If this condition continuous for a specified time period, the determination section in the control device 26 determines that the delivery rate of the pump 14 is greater than the supply rate of hot water into the tank 12, and the operation of the pump 14 is controlled to switch from high to low. Since the supply rate of hot water into the tank 12 then becomes greater, the flow rate control valve 25 throttles the flow to maintain the water level between the switches 23a and 23b. Therefore, there will be no such risk as permitting air to intrude into the pump 14 while it is being operated. |
